Renote island, Trégastel, Lannion, Côtes-d'Armor, Brittany, Francei

Regional Level Types
Renote island	Peninsula
Trégastel	Commune
Lannion	Arrondissement
Côtes-d'Armor	Department
Brittany	Region
France	Country

The average content of ilmenite (by weight) in the heavy sands is about 86%.

Renote Island (Enez Rennod in Breton) is an island in the Channel, belonging to the French commune of Trégastel, in the Côtes-d'Armor department, in Brittany. It is located on the Pink Granite Coast.

The peninsula has been occupied for 150,000 years, as evidenced by the Levallois flakes and scrapers from the Mousterian era unearthed here. A crec'h of a Neolithic troglodyte village is located on a property called Crech-Alia. 80 m to the NE is the gallery grave of Ty-al-Lia (or Ty-ar-Lia) which is not accessible because it is on private property. It is oriented east-west over a length of 12.75 meters and a width of 2.5 meters.

It was originally an island accessible at low tide, but the construction in 1885 of a causeway which connects it to the mainland, even at high tide, made it a peninsula.

Renote Island was classified among the “picturesque sites” within the meaning of the law of May 2, 1930 by a decree of February 11, 1977.

The island presents a granite block field which borders the water for around a hundred meters. The granite blocks sculpted by meteoric agents according to systems of subhorizontal and subvertical joints, give surprising reliefs with their arrangements defying the laws of balance and their shapes which have inspired the popular imagination, hence their local microtoponyms: "painter's palette", "whale head", "mushroom", etc. This block field constitutes a geological site of regional interest.

The block field is composed of pink granite with a grainy texture (multi-millimeter grain), which is in fact a granitoid of the syeno- or monzogranite type. Its paragenesis is: quartz, pink alkali feldspar (microcline), white feldspar (plagioclase), rare black micas of biotite and hornblende. Its alteration gives a granite grus visible at the foot of the rocks and locally called “perré”.

The top of these rocks is sometimes hollowed out by depressions. The almost permanent stagnation of rainwater enriched with salt from the sea spray gives these granite micromodels: basins, locally called "bidets of the Virgin" or "footprints of the Devil", in the form of microcirques, taffoni or basins often open on the sides by channels, grooves (comparable to limestone pavements), resulting from the flow of water which overflows and where lichens (Xanthoria parietina) settle. The erosion can be such that it pierces the rock, as in the “painter’s palette”. This pierced rock rests on a lower block covered with lichens, giving it a gray tint. The mechanical erosion of this granite is materialized by the contact zone between these two blocks. This probably corresponds to an old sub-horizontal joint very little altered over a few dm², while the alteration has sanded the entire rest of this fracture.

On the eastern coast, several rocks show at their base dark, layered metric enclaves (xenoliths), which are debris of enclosed sedimentary rocks. Between Castel Menguy and Le Gouffre, small veins of white quartz and aplite criss-cross the granite.

At Coz Pors beach, near the tip of Beg ar Vir, the rock in the shape of a large cube is nicknamed “Le Dé”. It shows scour cavities due to wind and sea spray, which sculpt its base.

The "ball" ("la boule") is located in a pile of rocks at the eastern end of Renote Island, facing Sept-Îles. Access is not easy and is only possible at low tide. This geological phenomenon is explained by marine erosion in an area not sheltered from waves and tides. The granite balls are then dismantled into smaller blocks and can produce pebbles with sometimes almost perfect ovoid shapes. The size of these pebbles depends mainly on two factors, the mesh of the joint network and the force of the waves.

Other Databases

Wikipedia:	https://fr.wikipedia.org/wiki/%C3%8Ele_Renote
Wikidata ID:	Q3593188

Other Regions, Features and Areas containing this locality

References